Francesco Frangialli is surely the busiest man in the world ever. He flew ten times around the world last year. But we've managed to coordinate a one-hour slot in his schedule, between New York and Namibia, in which we can pick him up from Geneva airport, drive him to the Chamonix glaciers and film him talking with a local expert about how far they've melted. Everything goes swimmingly... planes, hire cars, trains, equipment, expert, Francesco... until... fog. So we film him and expert talking about glaciers without being able to see any glaciers, even though they were towering behind them. It could have been Camden Town.

But the next day, the fog lifts (as FF lifts off to his next appointment) and we see the glaciers. Amazing. Astounding. Awesome. 85% already gone thanks to us and our cars. No chance of saving the rest.

We get the cable car up the mountain and meet an old woman in a cafe who brings out photos from the 1800s. The glacier looms over the whole town, bursting out of its valley. Now it's more of a melting ice-cream dropped in the road.

Alex (trusty assistant as Lizzie is on holiday) and I attempt to find the exact spot the old photos were taken, so we can film from there and then dissolve between the two in the final doc. We drive along an ever-narrowing path going up and up into the forest, not knowing why all the hikers are glowering at us. (Why do the French write their road signs in French, of all languages? And what does "interdit" mean?).

Anyway, we duly get stuck, and then Alex accidentally reverses one wheel over the edge of a - if not exactly cliff - very alarming drop. My charm and Franglaise is put to the severe test in enlisting one of the glowering hikers to help push the car back into safety. Funny how you get super-human strength just when you need it. (And forget to buy travel insurance just before you need it.) Two fags (both Alex) and one 243-point turn later, we scoot out of the nature reserve with our heads hanging low. And without the shot, as the fog came back.

But we're glad to be alive and so toast our survival in traditional Western style: going shopping. I'm beginning to realise that all my other films required me to look like my true self (toddler who refuses bathtime), whereas this one keeps calling for me to look smart. So I say goodbye to my 11-year-old fleece (bought for first ever adventure, mapping coral reefs in Africa) and buy a spanking new one, which comes with an instruction manual.